Development of Plucked New Shoot Yield and Components in Tea Leaves Estimation Technology Using a Portable NDVI Measuring Device (GreenSeeker 2)

Abstract

In Shizuoka Prefecture, a simple method to monitor the growth of tea plants for tea production is required because of the increase in the managed area per producer. In this study, we developed a technology for estimating the tea yield of plucked new shoots and their composition using a GreenSeeker 2 (GS), an inexpensive, portable NDVI measuring device.

The GS measurement conditions and the relationship between GS-NDVI and yield and between GS-NDVI and composition of the main variety 'Yabukita' were evaluated. In addition, estimation accuracy of 'Yabukita' and other varieties were verified; verification of errors among two devices of the same model was also conducted. The results showed that GS-NDVI was useful for estimating the yield of the first crop of 'Yabukita', because GS-NDVI was highly correlated with the yield. However, GS-NDVI might not be suitable to estimate the second tea crop yield because of the small change. Differences in estimation were observed among varieties other than 'Yabukita', suggesting the need to develop estimation formulas for each variety. In addition, measurement errors were observed between the two devices; however, they could be corrected.